5、service层接口与接口实现类
service层存放调用dao层的接口，和其名字一样，是为了方便用户操作数据库而设立的。而service层下也有impl层，存放service接口的实现类。
5.1、PersonService接口
package com.qj.service; import com.qj.entity.Person; import java.util.List; public interface PersonService { /** * * @param name 用户名 * @param pwd 密码 * @return 登录结果 */ boolean login(String name, String pwd); /** * * @return 返回查询结果集 */ List<Person> showAllPerson(); /** * * @param person 通过网页输入好友信息 * @return 返回受影响行数 */ int add(Person person); /** * * @param id 通过点击网页按钮删除 * @return 受影响行数 */ int remove(Integer id); }
5.2、PersonServiceImpl接口实现类
package com.qj.service.impl; import com.qj.dao.PersonDao; import com.qj.dao.impl.PersonDaoImpl; import com.qj.entity.Person; import com.qj.service.PersonService; import java.util.List; public class PersonServiceImpl implements PersonService { PersonDao pd = new PersonDaoImpl(); @Override public boolean login(String name, String pwd) { Boolean boo=false; Person p = pd.selectByName(name); if (p != null) { if (p.getPwd().equals(pwd)) { boo = true; } } return boo; } @Override public List<Person> showAllPerson() { return pd.selectAll(); } @Override public int add(Person person) { return pd.insertPerson(person); } @Override public int remove(Integer id) { return pd.deletePerson(id); } }
6、servlet包分为controller包和view包
由于servlet中的service方法具有两种参数：用户请求参数req和响应参数resp，因此把其分到两个包下更合理。
有关需求参数req放在controller包中，负责接收用户数据以及向view中传送数据
存入要传输的数据使用：req.setAttribute()
该方法含有两个参数，第一个是String类型，第二个是Object类型
用法相当于键值对：第一个参数存入键，第二个参数存入值
自动跳转路径使用：req.getRequestDispatcher().forward(req,resp)
该方法形参传入相对路径即可，以/开头
千万注意要加上后面的.forword(req,resp) (我老是忘加，导致数据无法传送)
有关响应参数resp放在view包中，接收controller包传送的数据并将效果显示到浏览器页面
获取req传送的数据使用：req.getAttribute()
该方法含有一个参数，需要输入传进来的键
由于值的类型是Object，通常需要进行类型强转
例如：boolean boo = (boolean) req.getAttribute("boo")
通过resp参数也可以进行网页的跳转，但是一般认为不能存入数据(存的非常有限)
resp.sendRedirect()
括号内填入绝对路径，也要以/开头
6.1、controller包下的四个servlet类
这里包引入情况基本一致，因此博文里只粘贴一次，此外要注意对外访问路径均采用注解的方式
6.1.1、LoninController类
package com.qj.controller; import com.qj.service.PersonService; import com.qj.service.impl.PersonServiceImpl; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException; @WebServlet("/login") public class LoginController extends HttpServlet { @Override protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { req.setCharacterEncoding("utf-8"); String name = req.getParameter("username"); String pwd = req.getParameter("pwd"); PersonService ps = new PersonServiceImpl(); Boolean boo = ps.login(name, pwd); req.setAttribute("boo", boo); req.getRequestDispatcher("/loginView").forward(req, resp); } }
6.1.2、AddPersonController类
@WebServlet("/addPerson") public class AddPersonController extends HttpServlet { @Override protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { req.setCharacterEncoding("utf-8"); String name = req.getParameter("name"); String QQ = req.getParameter("QQ"); String bz = req.getParameter("bz"); Person p = new Person(null, name, null, QQ, bz); PersonService ps = new PersonServiceImpl(); int n = ps.add(p); req.setAttribute("n", n); req.getRequestDispatcher("/addPersonView").forward(req,resp); } }
6.1.3、ShowPersonController类
@WebServlet("/showPerson") public class ShowPersonController extends HttpServlet { @Override protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { PersonService ps = new PersonServiceImpl(); List<Person> list = ps.showAllPerson(); req.setAttribute("list", list); req.getRequestDispatcher("/showPersonView").forward(req,resp); } }
6.1.4、DeletePersonController类
@WebServlet("/delete") public class DeletePersonController extends HttpServlet { @Override protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { int id = new Integer(req.getParameter("id")); PersonService ps = new PersonServiceImpl(); int n = ps.remove(id); req.setAttribute("n", n); req.getRequestDispatcher("/deletePersonView").forward(req, resp); } }
6.2、view包下的四个servlet类
6.2.1、LoginView类
package com.qj.view; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException; import java.io.PrintWriter; @WebServlet("/loginView") public class LoginView extends HttpServlet { @Override protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { resp.setContentType("text/html"); resp.setCharacterEncoding("utf-8"); PrintWriter pw = resp.getWriter(); boolean boo = (boolean) req.getAttribute("boo"); if (boo) { resp.sendRedirect("/MyfirstServlet/showPerson"); }else{ resp.sendRedirect("/MyfirstServlet/login.html"); } } }
6.2.2、AddPersonView类
@WebServlet("/addPersonView") public class AddPersonVIew extends HttpServlet { @Override protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { int n = (int) req.getAttribute("n"); if (n > 0) { resp.sendRedirect("/MyfirstServlet/showPerson"); } else { resp.sendRedirect("/MyfirstServlet/add.html"); } } }
6.2.3、ShowPersonView类
@WebServlet("/showPersonView") public class ShowPersonView extends HttpServlet { @Override protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { resp.setCharacterEncoding("UTF-8"); resp.setContentType("text/html"); List<Person> list = (List<Person>) req.getAttribute("list"); PrintWriter pw = resp.getWriter(); pw.println("<html><head><meta charset='utf-8'> </head><body>"); pw.println("ID 姓名 QQ    备注"+"<br>"); for (Person p : list) { pw.print(+p.getId()+" "); pw.print(p.getName()+" "); pw.print(p.getQQ()+" "); pw.print(p.getBeizhu()+" "); pw.print("<a href='/MyfirstServlet/delete?id="+p.getId()+"'>点击删除</a>"); pw.println("<br>"); } pw.println("<a href='/MyfirstServlet/add.html'>添加好友</a>"); pw.println("</body></html>"); pw.flush(); } }
6.2.4、DeletePersonView类
@WebServlet("/deletePersonView") public class DeletePersonView extends HttpServlet { @Override protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { resp.setCharacterEncoding("utf-8"); resp.setContentType("text/html"); int n = (int) req.getAttribute("n"); PrintWriter pw = resp.getWriter(); if (n > 0) { resp.sendRedirect("/MyfirstServlet/showPerson"); } else { pw.println("删除失败！"); } pw.flush(); } }
7、test包用来存放测试类(@Test)
在实战开发中为了提高调试效率会经常使用注解开发，给dao层或者service层阿进行方法测试
这里我就测试了一下添加和显示的功能：
package com.qj.test; import com.qj.entity.Person; import com.qj.service.PersonService; import com.qj.service.impl.PersonServiceImpl; import org.junit.Test; import java.util.List; public class PersonTest { PersonService ps = new PersonServiceImpl(); @Test public void showPserson(){ List<Person> list = ps.showAllPerson(); for (Person person : list) { System.out.println(person.toString()); } } @Test public void addPerson(){ Person person = new Person(null, "张三", null, "3110124130", "淳朴张"); int n = ps.add(person); System.out.println(n); } }
测试效果：
这里第一行的1意为成功插入一条数据，后面两条person属性就是数据库中的查询结果
8、前端整合
8.1、登录页面
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>添加好友</title> </head> <body> 输入好友信息：<br> <form action="/MyfirstServlet/addPerson" method="get"> 名字：<input type="text" name="name"><br> Q Q：<input type="text" name="QQ"><br> 备注：<input type="text" name="bz"><br> <input type="submit" value="添加"> </form> </body> </html>
8.2、添加好友页面
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>登录界面</title> </head> <body> <form action="/MyfirstServlet/login" method="get"> 登录账号：<input type="text" name="username"><br> 登录密码：<input type="password" name="pwd"><br> <input type="submit" value="提交"> </form> </body> </html>
9、数据库设计和项目效果展示
表格结构
登录界面
显示页面
添加好友界面
添加成功跳转至显示页面
删除好友并跳转至显示页面
以我目前所学就只能做到这儿了，项目虽然很简陋，但主要想分享给大家项目结构的构建。码文不易，希望能得到你们的支持，以此来激励我不断更文！
